Refrigeration



REFRIGERATION Filed Feb. 5, 1940 2 Sheets-Sliet 1 INVENTORGeoIyeA.DI'ace ATTORNEY Patented Mar. 3, 1942 REFRIGERATION George A.Brace, Winnetka, Ill., assignor to The Hoover Company, North Canton,Ohio Application February 5, 1940, Serial No. 317,378

13 Claims. This invention relates to the art of refrigeration and moreparticularly to an absorption refrigerating system involving uniquecontrol and regulating features.

This invention particularly relates to threefiuid absorptionrefrigerating systems of the type in which a circulating motor ishermetically sealed within the system in order to circulate the fluidstherein. Motors of this type must be lubricated. However, considerabledifficulty may arise in handling and installing the system due to thefact that under some circumstances the lubricant in the motor shell maybe displaced by foreign material, such as absorption solution, and oncedisplaced it will be very difficult to return the lubricant to itsnormal environment without materially reconstructing the apparatus.Moreover, it may occur that the system will not be maintained in uprightcondition during handling and installation with the result that thelubricant will be spilled out of the motor casing and will not later bereturned thereto.

In order to obviate these difficulties it is an object of the presentinvention to provide an absorption refrigerating system of the abovedescribed character in which the motor is lubricated by a material whichis not riuid at normal atmospheric temperatures and which will flow atthe temperatures maintained by the heat generated by the motor windingin order to perform its lubricating function efliciently. 1

Itis a further object of the present invention to provide an absorpticnrefrigerating system of the above referred to type in which thelubricant in its non-fluid state imposes sufficient drag upon therotating portions of the motor to block the same until the lubricant hasbeen liquefied or substantially so, for example by the application ofheat thereto.

It is a further object of the present invention to provide an absorptionrefrigerating system in which operation of the circulating motor isprevented after energization thereof by reason of the lubricant blockingthe motor for a period of time sufficient to permit the boiler to comeinto full opera-tion; that is, to discharge refrigerant vapor to thecondenser in order that the same may be liquefied and re-evaporated inthe evaporator to produce a useful refrigerating effect.

With some lubricants, such as those having a high paraflin content, theperiod required to liquefy the same by the heat generated by the smallcurrent flowing through the winding of the w motor is excessivewherefore it is an object of the present invention to provide a specialheating element which functions to come into operation substantiallysimultaneously with the boilerheater and which will render the motorlubricant fluid at substantially the same time that the boilerdischarges refrigerant vapor after which the motor will be energized andthe heating element de-energized to place the system in normal operatingcondition.

It is a further object of the present invention to provide an absorptionrefrigerating system including a circulator, the rotor of which isimmersed in a non-fiuid lubricant in which the lubricant is renderedfluid by waste heat from the boiler-heater at substantially the timethat the boiler comes into full operation; that is, dischargesrefrigerant vapor, and in which the motor is energized after thelubricant is rendered fluid and in response thereto in order to placethe system in normal operation,

It is still another object of the present invention to provide anabsorption refrigerating system which includes a lubricated circulatorprovided' with a lubricant heater for softening the lubricant, whichheater is tie-energized after softening of the lubricant in response totemperature change in a particular portion of the refrigerating systemwhen such a changeis produced as an incident to normal startingoperation of the refrigerating system.

Other objects and advantages of the invention will'become apparent asthe description proceeds when taken in connection with the accompanyingdrawings, in which:

Figure 1 is a diagrammatic representation of a three-fluid absorptionrefrigerating system embodying the present invention;

Figure'2 is a partial sectional elevational view drawn to an enlargedscale of the motor circulator unit illustrated in Figure 1;

Figure 3 is a partial schematic illustration of a modified form .of theinvention.

Referring now to the drawings in detail and first to Figure 1 thereof,there is illustrated a three-fluid absorption refrigerating systemcomprising a boiler B, an analyzer D, an air-cooled rectifier R, atubular air-cooled condenser C, an evaporator E, a gas heat exchanger G,a tubular inclined air-cooled absorber A, a liquid heat exchanger L, asolution reservoir S, and a circulating fan F which is driven by anelectrical motor M. These elements are suitably connected by variousconduits to form a plurality of gas and liquid circuits constituting acomplete refrigerating system to which reference will be made in moredetail hereinafter.

The above described refrigerating system will be charged with a suitableabsorbent, such as water, a suitable refrigerant, such as ammonia, andan inert pressure equalizing medium preferably a dense inert gas likenitrogen.

The boiler B is arranged tobe heated by a gas burner H which will bedescribed in more detail hereinafter. The application of heat to theboiler B generates refrigerant vapor from the solution thereincontained. The vapors so generated pass upwardly through the analyzer Din counterflow to the strong solution flowing downwardly therethrough.After traversing the analyzer D the vapor is conveyed from the upperportion thereof to the upper portion of the condenser C by means of aconduit II which includes the rectifier R.

The lean solution formed in the boiler by the generation of refrigerantvapor therefrom is conveyed from the boiler to the solution reservoir Sby way of the conduit l2, the liquid heat exchanger L and a finnedlooped conduit i3 which also serves as a solution precooler.

The solution reservoir 8 is vented by means of a'conduit H whichconnects to the suction conduit of the circulating fan F. The conduit l5extends between the suction side of the fan F and the upper portion ofthe absorber A.

The lean solution is conveyed from the reservoir S to the conduit l5adjacent its point of connection with the absorber A by means of a gaslift pumping conduit Ii. Pumping gas is supplied to the conduit l6 bymeans of a conduit I! which is connected between the discharge conduitit of the circulating fan F and the gas lift pump l6 below the liquidlevel normally prevailing therein and in the solution reservoir S.

The lean solution flowsdownwardly through the absorber A in counterflowrelationship to a richmixture of inert gas and refrigerant vapor whichis supplied to the bottom portion of the absorber from the evaporator ina manner to be described hereinafter.

In its traverse through the absorber the lean solution absorbsrefrigerant vapor from the gas mixture flowing therethrough and theresulting heat of absorption is rejected by the cooling flns to coolingair flowing over the exterior walls of the absorber vessel.

The strong solution thus formed in the absorber is conveyed therefrom tothe upper portion of the analyzer D by way of the conduit IS,

th liquid heat exchanger L, and a conduit thus completing the absorptionsolution circuit.

Lean inert gas is formed in the absorber A by the absorption ofrefrigerant vapor and is then conveyed from the upper portion of theabsorber to the suction side of the circulating fan F by means of theconduit 15. The inert gas is placed under pressure in the fan F and isthen conveyed therefrom to the lower portion of the evaporator E by wayof the conduit i8, the outer path of the gas heat exchanger G and anevaporator gas supply conduit 22.

The refrigerant vapor which is supplied to the condenser C is liquefiedtherein by heat exchange relationship with atmospheric air and is thenconveyed therefrom to the bottom portion of the evaporator E by way ofth conduit 23 anda conduit 2| which includes a downwardly extendingU-shaped looped portion which is designed to c: rry a liquid seal and apressure balancing column of the liquid refrigerant. The conduits 23[ill and II are vented by means of a conduit N to the rich gas side ofthe gas heat exchanger G. As a result of this construction the pressureprevailing in the condenser and the condenser side of the conduit 24 isthat prevailing on the discharge side of the evaporator whereas thepressure prevailing on the discharge side of the conduit 24 is thatprevailing at the inlet to the evaporator. This pressure difference iscompensated by a pressure balancing liquid column which is supported inthe condenser side of the conduit 24.

The evaporator E may be of any desired type of construction. However, asdiagrammatically illustrated herein, it is of the type in which the highvelocity gas stream flowing through the evaporator serves to sweep ordrag liquid refrigerant upwardly therethrough as it is evaporating toproduce refrigeration. A preferred construction of this type evaporatoris disclosed and claimed in the co-pending application of Curtis C.Coons and William H. Kitto, Serial No. 220,189, filed July 20, 1938. Ananti-blocking and overflow drain 21 is connected between the upperportion of the bottom conduit in the evaporator E and the strongsolution return conduit H.

The liquid refrigerant supplied to the bottom portion of the evaporatorE meets a high velocity gas stream flowing upwardly therethrough withthe result that the liquid refrigerant is propelled upwardly through theevaporator as it is evaporating into the gas stream to produce usefulrefrigeration. The top portion of the evaporator is provided with alarge diameter finned box-cooling conduit 28 into which both the liquidand gas discharge. The gas flows at a slow rate through this conduit,hence the same is inclined rearwardly in order to permit liquid to flowby gravity. The resulting rich gas and unevaporated material in theevaporator is conveyed from the conduit 10 into the rich gas side of thegas heat exchanger G by means of a conduit 2!. After traversing the richgas side of the gas heat exchanger the rich gas and unevaporatedmaterial is' drained therefrom into the bottom portion of the absorber Aby means of the conduit ll. Thus, the conduit 30 serves as a rich gasreturn conduit and as an evaporator drain. The rich gas then flowsupwardly through the absorber A in counterflow relationship with thelean solution flowing downwardly therethrough in the manner heretoforedescribed.

It will be noted that with the construction thus provided evaporatordrainage is conveyed to the conduit I! in a manner such that it cannotreach the circulating fan and the fan is so connected to the absorberthat lean solution cannot be conveyed thereinto from the lean solutionsupply lines. in preventing absorbing solution from finding its way tothe motor shell, as will be explained in more detail hereinafter.

Referring now to Figures 1 and 2, it is apparent that the fan casing Fcarries a sealed motor shell 35 depending therefrom. The motor Mconsists of a rotating element 36 which is mounted within the shell anda stationary fleld winding or stator structure 31 which is mounted onthe outside of the shell whereby the magnetic circuit for the inductionrotor 36 must pass through the shell 35. The rotor is supported onsuitable.bearing assemblies indicated generally at II and II within theshell II. The motor shaft 40 passes This is of considerable importancethrough the bearing 35 and carries a suitable fan within the fan housing4| in a conventional manner.

The depending motor shell 35 is filled with a suitable lubricant up tothe level of the line indicated generally at 44; that is, the rotor iscompletely submerged and part of the bearing 35 is submerged in thelubricant.

One such lubricant is paraiiin and it is obtainable in a long range ofmelting points and specific gravity. By selecting paraflin of the propermelting point or by mixing it with other lubricants, almost any meltingpoint desired can be obtained. This lubricant has the characteristicthat it is non-fluid at ordinary room temperatures but will become fluidwhen heated above that temperature in order to lubricate the bearings topermit the motor to rotate. In its non-fluid state the drag of thislubricant is sufficient to stall the rotor or the motor.

In this connection it should be emphasized that this motor is very smalland develops only sufllcient power to circulate the inert gas with a fewinches of water pressure differential, hence the lubricant drag iseasily suflicient to stall the same.

In order to apply heat to the lubricant which is contained within theshell 35 to render the same fluid, a suitable electrical heating element45 embraces the lower end of the motor shell 35 below the stator 31 ofthe electrical motor M.

The heater 45 is encased in a suitable refractory channel shaped element46 which protects the stator and. its associated windings from the heatof the element 45 and also prevents loss of heat therefrom.

A housing 41 of insulating material is suitably attached to the bottomportion of the motor shell 35 beneath the heater 45 and is provided witha switching enclosure or chamber 48. An electrical switch 49 is enclosedwithin the chamber 48. A bracket 50 is attached to the bottom portion ofthe shell 35 and carries a thermostatic strip or disc 5|, as may bedesired, directly above the switch 49. The disc 5| is provided with anactuating button 52 which may be made of a composition insulatingmaterial and is positioned to strike the movable element 53 of theswitch 49 to actuate the same.

'As was mentioned previously a heater H is provided for the boiler B.Gas is supplied to the heater H from a suitable source of supply througha conduit 55 which includes a s lenoid valve V. A small by-pass 55 isprovided around the valve V in order to maintain a small ignition flameon the heater H. Also included in the conduit 55 adjacent the burner isa suitable thermostatic safety cut-off device 51 which is arranged todiscontinue supply of fuel to the burner completely upon failure offlame thereupon, as for example in case the small igniting or pilotflame is extinguished by a draft or the like.

The apparatus is controlled by means of a suitable thermostaticswitching mechanism indicated generally at 50 and provided with acapillary conduit 5| which connects to a fluid containing bulb 52positioned to be influenced by temperature changes at or adjacent theevaporator E. The exact construction of the thermostatic switchingmechanism 50 is conventional 1 and need not be disclosed in detailherein. Power is supplied to the apparatus from a pair of electricalconductors 53 and 54. The conductor 53 connects directly to the solenoidvalve V which is then connected by means of a conductor to the switchingmechanism 55. The switching mechanism 55 is connected to the winding 55of the motor stator 31 by means of a conductor 51 and .a branchconductor 55. The switching mechanism 55 is also connected to theheating element 45 by the conductor 51 and a second branch conductor 59.

The heating element 45 is then connected to the upper contact 15 of theswitch 43 by means of a conductor 1|. The winding 55 of the stator 31 isconnected to the lower contact 12 of the switch 49 by means of theconductor 13.

As may readily be seen from a perusal of Figure 2, the movable element53 of the switch 49 is arranged to contact either the upper connector 10or the lower connector 12 thereof. The movable element 53 of the switch43 is connected directly to the supply conductor 54, thus completing theelectrical control circuit.

The operation of this form of the invention except insofar as the samehas already been disclosed in connection with the construction of therefrigerating apparatus per se is as follows Assuming a. demand forrefrigeration the thermostatic switch 55 will complete the electricalcircuit between the conductors 55 and 51. This will then energize thesolenoid valve V to permit full flame operation of the burner H.Likewise current will flow from the switching mechanism," by thefollowing circuits 51, 59, 45, 1|, 15, 53 and 54, thereby energizing theheater 45. Due to the fact that the thermostat 5| will be flexedupwardly, as shown in Figure 2, to permit contact between the elements53 and 10 of the switch 45, the heater will be in condition to beenergized but the winding 55 of the motor'will be open circuited at 12.Consequently heat will be applied to the boiler B to heat the contentsthereof to the boiling point after which refrigerant vapor will beproduced and heat will be applied by the element 45 to the shell 35 andthe contents thereof in order to render the lubricant fluid so that thesame will not block rotation of the rotor 35 upon energization of thewinding 55. The motor, heater, lubricant, boiler and boiler-heater areall inter-related in any given installation. Consequently with a givenlubricant, boiler and boiler-heater the heater 45 will be constructed torender the lubricant fluid substantially simultaneously with theexpulsion of refrigerant vapor from the contents of the boiler. When theshell 35 has been heated. sufliciently to render the lubricant thereincontained fluid, the temperature of the .shell will be at a valuesumciently to actuate the thermostat 5| which will then flex downwardly,as viewed in Figure 2, separating the contacts 53 and 15 and closing thecontacts 53 and 12, thereby de-energizing the heater 45 and energizingthe motor stator winding 55. The apparatus is now in normal operatingcondition and will continue in that condition until the temperature ator adjacent the evaporator has been lowered to the predetermined pointfor which the thermostatic switching mechanism 55 is set. Duringoperation of the apparatus the heat generated by the motor statorwinding is amply suflicient to maintain the lubricant in the fluidcondition and to prevent the same from imposing a stalling or blockingdrag upon the rotor 35.

When the temperature of the refrigerated space reaches that for whichthe control mechanism is set, the thermostatic mechanism 55 deenergizesthe entire system whereupon the valve V- closes, the burner H returns tolow flame or pilot flame operation and the motor is de-energized.

If the motor remains de-energized for an appreciable period of time. andit usually will remain de-energized for such a period of time, the motorwill cool sufliciently to cause congelation of the lubricant within theshell 88 and the thermostat 8| will consequently flex upwardly to theposition shown in Figure 2 to open the circuit between the connectors 12and 188 and to close the circuit between the connectors 18 and 83,

thereby re-conditioning the electrical circuit for normal startingoperation.

As at present advised the illustrated construction isthe preferredarrangement; however, the thermostatic cut-out for the lubricant heatermay be arranged to de-energize the heater in response to a change in thecondition of another portion of the system induced by energization ofthe system. For example, the thermostatic cut-out for the lubricantheater could be arranged to respond to the temperature of some portionof the pipe II. This pipe is heated by hot vapor enroute to thecondenser. There is a time lag between initiationof full flame operationof the burner and heating of this pipe which will allow sufilcientheating of the lubricant to render the same fluid and will produce thedesired lag in operation of the motor with respect to the burner.

those portions of the apparatus which have been altered are illustratedin Figure 3 in order to avoid unnecessary duplication of illustration.Certain portions of the apparatus .illustrated in Figure 3 beingidentical with apparatus previously illustrated and described in Figures1 and 2, they are given the same reference characters primed.

In the form of the invention illustrated in Figure 3 the products ofcombustion from the heater H are discharged through a central flue 88 ofthe boiler B. After traversing the flue 88 the products of combustionare conveyed to a suitable point of disposal by means of an insulatedflue system 8|.

The flue 8| joins a valve chamber 82 which is located'adjacent the motorM. The valve chamber 82 is branched, one branch 88 extending upwardlyinto communication with a shell which surrounds the lower portion of themotor shell 88' and in turn communicates with an off-take flue 88 whichultimately discharges into a flue 88 which conveys products ofcombustion to a point of ultimate disposition. The valve chamber 82 alsocommunicates with a branch conduit 81 which communicates with the lowerend of the flue 88.

A flap valve 88 is pivotally mounted within the valve chamber 82 and isarranged to be actuated by means of a crank 88 which connects to anactuating rod 88. I

The end of the rod 88 remote from the crank 88 carries an electricalswitch contact 8| which is adapted to qnake contact with a stationarycontact 82.

In this form of the invention electrical energy is supplied to theapparatus through the line conductors 88 and 88. The conductor 84 isconnected to a thermostatic switch mechanism 88 by means of theconductor 88. It will be understood that the thermostatic switchmechanism 88 will be positioned to respond to the temperature oi. theevaporator or of the space being refrigerated as may be desired. Theother side of the thermostatic switch 88 is connected by means of aconductor 81 to a solenoid 88 which is then connected by means ofa'conductor 88 to the other line conductor 88.

The conductor 88 also connects to aconductor I88, one end of which isconnected to the valve V and the other end of which is connected to onecontact of a solenoid operated switch IN. The valve V is also connectedby means of a conductor I82 to a second solenoid operated switch I88.The switches MI and I88 are arranged to be opened. or closedsimultaneously by means-of a solenoid armature I88 which is arranged tobe actuated by the solenoid coil 88.

The other contact of the solenoid switch I88 is connected to theconductor 88 by means of a conductor I88. The other contact of thesolenoid switch I" is connected to the contact 82 by means of aconductor I88. The movable contact 8| is connected to the field winding88' of the stator 81' of the motor M by means of a conductor I81. Thewinding 88 is also connected directly to the line conductor 88. Thiscompletes the electrical control circuit.

The actuating arm 88 of the valve 88 and switch contact 8| is arrangedto be operated by means of a thermostatic bellows 8 which is arranged tobe responsive to the temperature of the motor shell 88' by means of abulb and capillary tube connection I and is connected to operate the arm88 by means of a snap-acting toggle mechanism II2.

It is readily apparent that the switch contacts 8| and 82 are in opencircuit position; that is, in a position to de-energize the motor whenthe thermostatic bellows I I8 has contracted in which position it hasactuated the rod 88 to shift the valve 88 in position to closecommunication between the conduits 81 and the valve chest 82.

The operation of this form of the invention is as follows: Assuming ademand for refrigeration the thermostatic switch mechanism 88 will closethe circuit between the conductors 88 and 84, thus energizing thesolenoid coil 88. Upon energization of the solenoid coil 88, thesolenoid I88 will be lifted and the solenoid switches Ill and I88 willbe moved to closed circuit position. The valve V will now be energizedby the followin circuit: 88, I88, I82, I88, I88, 88 and 88. This circuitwill of course cause full flame operation to be initiated at the burnerH in the usual manner. However, the motor M is not yet energized due tothe open circuit condition existing at the electrical contacts 8| and 82and the valve 88 will be in the position illustrated in Figure 3wherefore waste products of combustion from the burner H will traversethe conduit 8|, valve chest 82 and conduit 88 in order to pass throughthe motor shroud 88 to heat the motor shell 38' and the oil thereincontained. This condition oi operation will continue until such time assufficient heat has been applied to the shell 38' in order to render thelubricant therein contained fluid and thus to remove the blockinginfluence from the motor. Once this condition is reached the temperatureof the shell 88' reaches a value sufficient to cause expansion of thethermostatic device 8 which then, through the snap-acting mechanism II2,quickly closes the electric contacts 8| and 82 and shifts the valve 88to the I00, IM, I06, 92, 9|,

dotted line position of Figure 3, thereby preventing further dischargeof products of combustion around the shell 36' and directing all theproducts of combustion directly to waste through the conduits 81 and 88.

The closure of the electrical circuits between the contacts 8| and 92now energizes the electrical motor M through the following circuits: 94,

I01, 66' and 93.

The system is now in normal operation and continues in that conditionuntil such time as the evaporator or the space being refrigerated shallhave reached a temperature for which the thermostatic switch 95 is set,whereupon the same will open allowing the solenoid to drop and opencircuit the solenoid switches IM and I03, thus de-energizing both theburner H and the circulating motor M. During operation of the systemsuflicient heat is applied to the shell 35' by the winding 66 of themotor M to maintain the lubricant therein in a fluid condition in orderthat the same may perform its lubricating function without imposing astalling load upon the very small motor which is utilized.

After de-energization of the system the shell 35' and its contents willgradually cool which will allow the lubricant to become non-fluid andeventually will reach a temperature such that the thermostat H willcontract to the position shown and will correspondingly actuate thevalve 80 to the position illustrated and'will open circuit the contacts9| and 92, thus restoring the system to its initial position andrendering the same in condition for re-energization with response to ademand for refrigeration. I

Though the bulb II I in this form of the invention has been illustratedas being applied directly to the motor shell 36 as that is nowbelieved'to be the preferred construction. it is obvious that the samecould be applied to other portions of the system, for example, one ofthe flues 8!, *85, 86 and the like.

The present invention provides a very advantageous arrangement in thatloss of lubricant from the motor shell and/or displacement thereof byliquid refrigerant or absorption solution during transit of therefrigerating system and installation thereof is absolutely prevented byreason of the fact that the lubricant is in a nonfiuid state prior tooperation thereof. This is of considerable importance as it isimpossible to insure that the apparatus will be maintained in uprightposition during handling and shipment.

The lubricant also has an advantageous effect with respect to theoperation of the refrigerating system and control thereof in that thearrangement herein provided automatically prevents circulation ofabsorption solution and inert gas until the boiler has been fully heatedandv liquid refrigerant has been supplied to the evaporator at whichtime the system is conditioned to go into complete operation.Considerable loss is entailed if the inert gas is circulated during. theperiod of time required to bring the liquid in the boiler up to theboiling temperature because this circulates absorption solution therebycontinuously removing the heated liquid from the boiler circulates inertgas warmed by contactwith the solution in the absorber through theevaporator thus adding to the net refrigerating load when advantageousconstruction of an absorptionrefrigerating system together with thecontrol mechanism therefor which insures that lubricant will not be lostfrom the motor shell during transit, handling and installation and whichprovides a construction whereby the lubricant is rendered fluid prior toenergization of the motor and also in which the time period required tocondition the motor for energization is so correlated through thecontrol for the boiler-heater that the boiler, is brought up tooperating condition just prior to energization of the motor whereby thesystem goes into complete operation immediately the motor is energizedand no loss of heat is entailed in the preliminary heating of the boileranalyzer assembly.

This type of control is not only economical but is also more efflcientthan the previously known simultaneous energization type of controlswhich have been used on this type of refrigerating system.

While the invention has been illustrated and described herein inconsiderable detail, various changes may be made in the arrangement,construction and proportion of parts without departing from the spiritof the invention or the scope of the appended claims.

I claim:

1. Absorption refrigerating apparatus including a boiler, an absorber, aliquefier and an evaporator connected in circuit, means for heating saidboiler, a motor driven iiuid circulator including a motor rotor sealedvin said apparatus and at least partially immersed in a lubricant v andcooling the same in the absorber and it also liquid refrigerant iseventually supplied to the evaporator. The present arrangement obviatesthese dimculties.

Thus, the present invention provides a very which has a viscositysufficiently high at atmospheric temperatures to prevent operation ofsaid rotor, means for heating said lubricant sufliciently to lower theviscosity thereof to a value such that operation of said rotor is notprevented thereby, refrigeration demand responsive means for energizingsaid boiler and lubricant heating means, and means for energizing saidmotor and for rendering said lubricant heating means inoperative inresponse to a change in the thermal condition of a portion of theapparatus induced as a consequence of energization'of said heaters,

2. Absorption refrigerating apparatus including a boiler, an absorber, aliquefier and an evaporator connected in circuit, means, for heatingsaid boiler, a motor driven fluid circulator including a motor rotorsealed in said apparatus and at least partially immersed in a lubricantwhich has a viscosity sufiiciently high atatmospheric temperatures toprevent operationof said rotor, an electrical heater for saidlubricant'sufficiently to lower the viscosity thereof to 8;;Yalue suchthat operation of said rotor is not prevented thereby, refrigerationdemand responsive means for energizing said boilerheating means andlubricant heater, and means for energizing said motor and for renderingsaid lubricant heater inoperative in response to a change in the thermalcondition of a portion of the apparatus induced as a consequence ofenergization of said heater.

3. Absorption refrigerating apparatus including a boiler, an absorber, aliquefier and an evaporator connected in circuit, a combustible fuelpheric temperatures to prevent operation of saidv rotor, means forconducting waste products of combustion from said boiler into heatexchange relationship with said lubricant to heat said lubricantsufficiently to lower the viscosity thereof to a value such thatoperation of said rotor is not prevented thereby, and means fordiverting said products out of heat exchange relation with saidlubricant when the same has been rendered fluid.

5. Absorption refrigerating system comprising an inert gas circuitincluding an evaporator and an absorber, a solution circuit including aboiler and said absorber, means for liquefying refrigerant vaporproduced in said boiler and for supplying the liquid to said evaporator,means for heating said boiler, a motor driven fluid circulator includinga motor rotor sealed within said system and immersed in a lubricantwhich is substantially solid at atmospheric temperatures, means forheating said lubricant for rendering the same fluid, refrigerationcontrol means for controlling the operation of said boiler and lubricantheating means, and means responsive to the temperature of said lubricantfor de-energizin said lubricant heating means and for energizing saidmotor when said lubricant is rendered fluid.

6. Absorption refrigerating system comprising an inert gas circuitincluding an evaporator and an absorber, a solution circuit including aboiler and said absorber, means for liquefying refrigerant vaporproduced in said boiler and for supplying the liquid to said evaporator,means for heating said boiler, a motor driven fluid circulator includinga motor rotor sealed within said system and mounted in a lubricant whichis substantially solid at. atmospheric temperatures, means for heatingsaid lubricant for rendering the same fluid, refrigeration control meansfor controlling the operation of said boiler and lubricant heatingmeans, means responsive to the temperature-of said lubricant forde-energizing said lubricant heating means and for energizing said motorwhen said. lubricant is rendered fluid, said lubricant being maintainedin fluid condition by the heat generated by said motor.

7. Absorption refrigerating system comprising an inert gas circuitincluding an evaporator and an absorber, a solution circuit including aboiler and said absorber, means for liquefying refrigerant vaporproduced in said boiler and for supplying the liquid to said evaporator,a combustible fuel burner for heating said boiler, a motor driven fluidcirculator including a motor rotor sealed in said system and contactedby a lubricant which is non-fluid at atmospheric temperatures, means fordisposing of waste products of combustion from said boiler including abranch in heat transfer relationship with said motor and a branch not inheat transfer relationship with said motor, control mechanism forregulating the operation of said fuel burner, and control mechanism fordirecting waste products of combustion through said branch in heattransfer relation with said motor until said lubricant is rendered fluidand for then directing such products through the said branch not in heattransfer relationship with said motor.

8. Absorption refrigerating system comprising an inert gas circuitincluding an evaporator and an absorber, a solution circuit including aboiler and said absorber, means for liquefying refrigerant-vaporproduced in said boiler and for sup-' plying the liquid to saidevaporator, a combustible fuel burner for heating said boiler, a motordriven fluid circulator including a motor rotor sealed in said systemand submerged in a nonfluid lubricant which is nonfluid at atmospherictemperatures, means for disposing of waste products of combustionfromsaid 'boiler including a branch in heat transfer relationship with saidmotor and a branch not in heat transfer relationship with said motor,control mechanism for regulating the operation of said fuel burner,control mechanism for directing waste products of combustion throughsaid branch in heat transfer relation with said motor until saidlubricant is rendered fluid and for then directing such products throughthe said branch not in heat transfer relationship with said motor, saidlubricant being maintained in fluid condition by the heat generated bysaid motor.

9. Absorption refrigerating apparatus including a boiler, an absorber, aliquefler, a motor driven fluid circulator and an evaporator connestedin circuit, means for heating said boiler, said motor driven fluidcirculator including a motor rotor sealed in said apparatus and immersedin a lubricant which has a viscosity at atmospheric temperatures suchthat operation of said rotor is prevented, means for conveying wasteproducts of combustion from said boiler heating means into heat exchangerelationship with said lubricant to heat said lubricant sufficiently tolower the viscosity thereof to a value such that operation of said rotoris not prevented thereby, refrigeration demand responsive means forenergizing said boiler heater, and means for energizing said motor andfor diverting waste products of combustion through a disposal path notin heat exchange relationship with said lubricant in response to achange in the thermal condition of a portion of the apparatus induced asa consequence of energization of said heaters.

10. Absorption refrigerating apparatus momprising a boiler, a liquefler,an evaporator and a condenser connected in circuit, a fluid circulatorcent for said driving device, means for heat'ml said generator, meansfor heating said lubricant,

control means'for rendering said heating means operative in responseto'a demand for refrigeration, and means responsive to a change in thecondition of a part of said apparatus induced as a consequence ofoperation of said heating means for rendering said lubricant heatingmeans inoperative and for rendering said driving device operative.

11. Absorption refrigerating apparatus comprising a boiler, a llquefler,an evaporator and a condenser connected in circuit, a fluid circulatorsealed in said apparatus, a driving device for said fluid circulatorsealed in said apparatus, a lubricant for said driving device, means forheatins said generator, means for heating said lubricant with waste heatfrom said generator heating 2,274,972 in the condition of a part oi saidapparatus induced as a consequence oi operation of said heating meansfor rendering said lubricant heating means inoperative and forrendering. said driving device operative.

12. Absorption refrigerating apparatus comprising a boiler, a liquefler,an evaporator and a condenser connected in circuit, a fluid circulatorsealed in said apparatus, a driving device for said fluid circulatorsealed in said' apparatus, a lubricant for said driving device, acombustible fuel burner for said generator, means arranged to heat saidlubricant with waste products of combustion from said fuel burner,control means for rendering said fuel burner operative in response to arefrigeration demand, and means responsive to a change in the conditionof a part of said apparatus induced as a" consequence of operation ofsaid fuel burner for diverting waste products of combustion away fromsaid lubricant heating means and for rendering said driving deviceoperative.

13. Absorption refrigerating apparatus comprising a boiler, a liquefler,an evaporator and a condenser connected in circuit, a fluidcirculatorsealed in said apparatus, a magnetically driven device fordriving said fluid circulator sealed in said apparatus, a magnetic fieldproducing means positioned exteriorly of the fluid retaining walls ofsaid apparatus for applying a magnetic driving force to saidmagnetically driven device, a lubricant for said magnetically drivendevice, means for heating said generator, means for heating saidlubricant, control means for rendering said heating means operative inresponse to a demand for refrigeration, and means responsive to a changein the condition of a part oi said apparatus induced as a consequence ofoperation 01' said heating means for rendering saidlubricant heatingmeans inoperative and tor energizing said magnetic fleld producingmeans.

GEO. A. BRACE.

